Few commercial radio listeners suspect that they're being exposed to progressive rock. But whenever a song by Yes, Jethro Tull, Pink Floyd or Emerson Lake & Palmer hits the airwaves on WDVE-FM, that's exactly what happens.

Those bands, along with edgier ones such as King Crimson, Nektar and Renaissance, make up the cream of the so-called prog-rock genre, which in its '70s heyday dominated the album-oriented rock (AOR for short) radio format, sold millions of albums and packed large concert halls and arenas (some bands, such as Rush and Genesis still do). So where are all the fans who followed that music, and why isn't it as overwhelmingly popular as it used to be?

The answer to the first question is easy -- the audience is still around but has aged, ranging from their late 40s to early 60s. The second involves the music industry's tendency to cater to youthful trends, a problem promoter Howard Levy, 50, is determined to solve.

You see, prog-rock never really went away. In the '80s, its second wave went pop (see Marillion's "Kayleigh") but was outmatched by New Wave and modern rock, and in the '90s, alternative and grunge styles forced the prog genre underground into its own hermetically sealed indie label ghetto. Above-ground glimpses, such as Dream Theater and Queensryche, would occasionally emerge, but Gen-X took the studiously proficient aspects it admired from prog-rock and created other scenes, from math-rock (Don Caballero) and post-rock (Godspeed You Black Emperor!) to new arena heroes Radiohead. Today, technically complex bands from Dillinger Escape Plan to Coheed & Cambria fill that prog niche for Gen-Y rock fans.

So who likes bands that still possess that classic '70s sound? Tons of people in Europe and Japan, where '90s-era prog bands such as Spock's Beard and Porcupine Tree can mount tours. And in North America, where much of the audience represents older, stay-at-home CD buyers, the live market is sated by one-off fests under such names as ProgDay (Chapel Hill, N.C.), ProgPower (Atlanta), BajaProg (Mexico) and CalProg (Whittier, Calif.). Pennsylvania is especially crowded, with RoSFest (outside Philadelphia) and the highly respected NEARFest (in Bethlehem).

But Levy saw a need to create yet another festival in Pittsburgh, which is why he's sponsoring the area's first Three Rivers Progressive Rock Fest this weekend. "In 2006, I went to my first NEARFest. I had an amazing time -- it made me feel like I was in a music camp for the weekend. I got to hear bands I've known, and ones I didn't know," he says

Levy missed the opportunities he once enjoyed, seeing prog-rock bands both in his native New York and his adopted Pittsburgh. "When I first came here [28 years ago], there were cool places -- you still had the Stanley, Graffiti, the Syria Mosque, the Decade, and the sound in those venues was good. In today's environment, there's less places for bands to play that fit that quality of sound and venue size, although we do have the Rex, Mr. Small's, Club Cafe, and the theater in Homestead."

With those choices, and a burning desire to create his own festival, why fixate on the Pepsi-Cola Roadhouse, near the Post-Gazette Pavilion? He was investigating a number of places, he says, when he was introduced to Jeff Jones, who does the sound and lighting at the Roadhouse, which he quickly noted was 15 minutes from the airport hotels and had plenty of easy parking.

Jones introduced Levy to Ray Bologna, who runs the Roadhouse. "They're used to doing country and western, and they do a dinner-and-show type of thing, which wasn't what I had in mind at all.'' But 15 minutes after Levy presented his proposal for the festival, "Jeff called me saying, 'Ray's very excited. I've never seen him like this.' "

Levy made some key alterations to the venue setup to enhance the festival format for maximum viewing and listening. Vendors -- band merchandise, Guitar Center and a Utah-based CD distributor called Syn-Phonic -- will be located all around the walls on the inside, with the tables skirted and a sign on each of them. "The seating is semi-in-the-round, with no seat more than 60 feet from the stage. There won't be any food or drinks in the venue -- those will be in a big tent outside the exit doors."

His vision included inviting some of the top independent prog acts, almost all of whom have played Pittsburgh at some point but never all in the same place. He knew he could count on 200 to 300 prog fans who attended other festivals to fly in and make up probably 85 percent of his ticket sales.

But the local component is just as crucial, and Levy wanted to mine that potential. "There are maybe 200 people around here who might go see Carl Palmer or Allan Holdsworth or the Flower Kings. And I needed to try to attract interest from the music scene here."

To that end, Levy held a battle of progressive bands on June 1 at the RPMs club in Bridgeville, which was won by local art-rockers Kalon. In addition, Levy invited club staples The Mandrake Project (who claim a wider range of influences, such as John Cage and Angelo Badalamenti) and jazz-rock session kings Manifesto (including drummer Tim Malone of 18 Names). Glaringly missing are the area's foremost proggers, Persephone's Dream. "The timing was bad," says Levy. "Around the time I talked to them, they had lost their bass player, so it was a missed opportunity."

Yet the lineup Levy cemented is formidable for his first time out, starring Sweden's Flower Kings and the percussion-heavy prog fusioneers Gongzilla (who claim lineage from Pierre Moerlen's offshoot of the '70s band Gong). He also hints at special surprises, such as a guest appearance by Dream Theater drummer Mike Portnoy, and a rare reunion of Neal Morse (who became a born-again Christian rocker) with his former bandmates in Spock's Beard.

Unfortunately, you'll never find a worthy melodic outfit such as Spock's Beard on WYEP (which doesn't carry prog-rock programming, though it's targeted to a similar demographic) or the regular WDVE rotation. But Levy went ambitiously mainstream with his promotion, blanketing commercial radio and newspapers with ads. And it paid off -- Spock's Beard will play acoustic on WDVE's morning Coffeehouse show this Friday, reaching way more potential listeners than a poster on Hollowood Music's bulletin board ever could.

So the final question is -- with Levy shouldering pretty much the entire financial burden of the event, will he emerge unscathed enough to want to try it again? "The future of it depends on the local response," he says.

"There'll be people coming from all over who go to the other festivals, but to build something in Pittsburgh, you need to have some type of base. ... If can build a base of 300-400 people from the area, that's enough to draw from" to allow for events between festivals, such as one-night shows with locals and international bands brought in as headliners. "I've also seen people bringing their college-age and high school-age kids to these shows lately, and that's where the future lies."